Using census tract data from the 1970 Census of Population, the degree of residential segregation between ethnic groups in thirty-one Standard Metropolitan Statistical Areas will be ascertained. These are all of the SMSAs meeting selection criteria developed to assure an adequate representation of ethnic groups in the communities. The patterns of segregation will then be examined in order to assess the extent that urban economic structure, as reflected by the communities' functional specialization, and the transportation era in which those communities developed has an impact on their residential structure.